The present invention generally relates to a cell analyzing apparatus. More particularly, the invention concerns a cellular analysis system suited for recognizing images of blood cells for discrimination of normal and abnormal cells from each other, classification of blood cells as well as counting thereof for the purpose of diagnostically determining blood diseases such as leukemia, anemia or the like.
In the hitherto known cellular analysis apparatus, the image of a blood cell is picked up by means of a microscope equipped with a television camera to derive chromatic density information of the blood cell image for thereby extracting the characteristic features such as cell area, peripheral length, nuclear area and others. On the basis of these extracted characteristic quantities, a relationship between the nuclear area on one hand and the ratio of the squared nuclear peripheral length to the nuclear area and the like are determined for recognition and classification of the blood cell under test.
Blood contains various components such as white blood cells, red blood cells, platelets and others. In conjunction with the detection and classification of the various blood cells, there are known various effective staining methods for the respective blood cells. The classification of the blood cells and discriminative identification of normal and abnormal cells by means of the cell analyzing apparatus are practiced after staining the blood cells by the respective effective staining methods. As the staining methods which are effective for the variety of blood cells, there are known those methods as mentioned below. For the classification of normal white blood cells (six species) and red blood cells (three species) as well as for the counting of platelets, May-Grunwald-Giemsa staining is adopted. On the other hand, for the counting of recticulocytes, a supravital staining method is employed. Further, for the detection of the abnormal white blood cells, i.e. blasts and immature cells which will appear in the case of leukemia, a peroxidase staining method is adopted.
In the hitherto known analytical examination of the blood cell images which have, a set of stained samples undergone the various stainings mentioned above are prepared, wherein the classification of the blood cells and discriminative determination as to the normal or abnormal cell are practiced for the individual stained samples, respectively. For example, after the classification of white blood cells based on the sample stained by the May-Grunwald-Giemsa method, the cell images of the sample stained supravitally are examined by changing the analyzing procedure. The same holds true also in the case of the sample stained by the peroxidase method.
Through the analyses of the blood cell images by using the variety of stained samples mentioned above, abnormal ratio among the six species of white blood cells, detection of abnormality indicated by the presence of immature cells and blasts, recognition of the normal blood cells, detection of indistinct or indefinite cells possibly produced by failure in the staining or physical injuries and others can be accomplished.
The sample which has proved to contain the abnormal and/or indefinite cells as the result of the analysis performed as mentioned above, are subjected to visual examination by a technician after mechanical retrieval to make a decision as to whether the sample indicates hemopathy (blood disease). In a hitherto known cellular analysis system exemplified by the one described in U.S. Pat. No. 3,851,972 issued on Dec. 3, 1974 and entitled "Automatic method and system for analysis and review of a plurality of stored slides", slides of samples prepared through a specific staining process undergo analysis of cells, whereby the slide in which an unidentifiable or abnormal cell has been found is memorized together with the position or location of the cell. After the whole analysis procedure has been completed, the slide in concern is retrieved and placed again in the microscope to review the unidentifiable cell through visual inspection. According to this known review system, a number of slides are at once automatically analyzed and subsequently a set of slides which are to be reviewed are subjected to visual inspection en bloc for the purpose of reducing the time required for the examination.
In connection with the hitherto known cell analyzing system, it should be mentioned that the number of cells analyzed automatically for a single sample is ordinarily about 100 per slide for one sample. This is because the time taken for the examination will become increased intolerably in case a greater number of cells are to be examined. In particular, in the inspection institutions such as hospitals where a large number of samples have to be handled, the number of cells to be analyzed is selected to be about 100 from the standpoint of efficiency to be realized in the examination.
In general, a major portion of the slides of samples to be examined in a hospital in a day, i.e. 90% or more of the samples picked from ordinary patients have proved to be essentially normal when inspected by a doctor or technician. However, even these normal samples each contain the unidentifiable cells in the ratio of 1 or 2 to 100 cells due to failure in the staining and/or physical injuries. Under the circumstances, 90% or more of the samples loaded in the cell analyzing apparatus require the visual inspection by a doctor, involving a lot of time and thus providing a great obstacle in enhancing the efficiency of the cellular analysis system.
Further, the hitherto known cell analysis system can scarcely ensure satisfactory statistical accuracy to the results of analysis because the number of cells to be automatically analyzed for one stained sample is generally about 100 per slide. Consequently, although no problem arises for clinical examinations in the case of a normal sample, there exists a possibility of abnormal cells being overlooked in the sample which was picked from a patient suffering hemopathy. Thus, the review through the visual inspection by a technician does not necessarily lead to the result of an examination which can assure a high reliability.